WASHINGTON — The upcoming inauguration of Barack Obama is an attractive target for international and domestic terrorists, but U.S. intelligence officials have no information about specific threats to the Jan. 20 event.

An internal intelligence assessment, obtained by The Associated Press on Wednesday, says the high visibility of the event, the presence of dignitaries and the significance of swearing in the country's first black president make the inauguration vulnerable to attacks.

What concerns analysts most, the report says, is the potential use of homemade bombs, a hostage situation or suicide bombers.

While security will be tight around the U.S. Capitol, the joint FBI and Homeland Security assessment says nearby hotels, public gatherings, restaurants and roads could be vulnerable to some kind of attack.

Most security everHomeland Security Secretary Michael Chertoff said security concerns during inaugurations have been elevated since the 2001 terror attacks. "I think it will be the most security, as far as I'm aware, that any inauguration has had," Chertoff said in an interview with the AP.

Chertoff also said there is no specific intelligence pointing to terrorist plots during the event.

"We have scrubbed very hard to look at anything that would suggest a credible, imminent threat or one that was specifically focused on the inauguration," Chertoff said, though not referring to the intelligence assessment. "We're not, at this point, aware of a credible, specific, imminent threat that would affect the inauguration."

The Secret Service, which is in charge of the overall security for the event, announced Wednesday that bridges into Washington and about 3.5 square miles of the downtown will be closed on Jan. 20. The security perimeter covers more of the city than previous inaugurations.

The analysis says that threats against Obama have increased since he was elected, which also poses concern for the inauguration.

Lone wolf threatsAccording to the intelligence assessment, a so-called lone wolf poses the greatest threat during the inauguration because such criminals are generally not affiliated with any specific group or act without the direction of a group. There have been some lone wolf threats reported, but nothing points to a well-planned plot, the assessment said.

Officials are concerned about explosives placed in crowded areas and people impersonating emergency and law enforcement officials, but they have no specific information that indicates terrorists are planning to do this, the assessment said.

While intelligence officials have seen no credible threats to the event from international terrorists or domestic terrorists, al-Qaida and its affiliates remain a threat to U.S. interests within the country and abroad, and the significance of Obama's presidency raises the potential threat from hate groups.

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